REST quiz of the day: which is more important when following REST: updating the resource state or updating state on the client? Most developers are likely to say that REST focuses on updating resource state on the server. After all, POST, PUT, and DELETE all do so. GET is the only HTTP verb that fetches resource state without changing it.

If you've been reading ZapThink's discussion on REST, you probably realize that those developers are incorrect. Updating resource state is clearly an important part of REST, but updating state on the client is even more important. Why? Because client state is the foundation for distributed hypermedia applications. And after all, such applications are the point of REST.

In fact, the RESTful world distinguishes between resource state and application state, which is the state information the client maintains. And since hypermedia are the engine of application state, it makes sense that application state is more important to REST than resource state. After all, REST is representational state transfer. The representations are what the resources send to the clients, including application state information that belongs on the client.

HATEOAS and the CloudThe topic of application state came up in an interesting discussion during our recent Cloud Computing for Architects course in San Diego. I was explaining how it's important to maintain a stateless application tier in the Cloud, because we want to put the components on that tier (Web servers, application servers, ESBs, etc.) onto virtual machine (VM) instances. In order to achieve the elasticity and resilience of the Cloud, then, we can't afford to maintain state information on such instances. We always have the option of persisting such state information, making it a part of the resource state, but relying too heavily on our resource state limits our scalability. The clear alternative is to transfer state information to the client, and let hypermedia be the engine of application state (otherwise known as the dreaded HATEOAS REST constraint).

One of the attendees in the class was confused by this discussion. He pointed out that if we use the client (say, a browser) to maintain state in a stateful application like an eCommerce shopping cart, then such state information must either go into hidden form fields or into the URL, so that the server can pass it along to the browser from one request to the next. But if the user is clicking a link rather than submitting a form, then they are executing a GET, and with a GET, the only place to put state information from the client to the server is in the URL. And we all know that URLs have a maximum length. What do we do, he asked, if we have too much state information for the URL? For example, we might have dozens of items in our cart. Was I suggesting passing the entire contents of each cart - product descriptions, prices, etc. - in the URL?

The answer, of course, is no. I say "of course" because such a question would be silly for anyone who truly understands REST. But I must admit, it took me a while to think through my response. The problem was that I have a background as a Web developer, and my student may have also built his share of Web sites back in the day as well. And back in the 1990s, before REST, in the early days of HTML and JavaScript, maintaining state in a browser was problematic. All we had were cookies and the aforementioned hidden form fields and URL query strings. And since people can turn their cookies off, we never wanted to rely on them. So yes, back in the day, if the user is clicking a link (i.e., performing a GET), the URL was all you had to work with.

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With REST, however, we're working with an abstracted client. It need not be a browser, and in fact, it need not have a user interface at all. A RESTful client may serve as an intermediary, for example. Even when the client has a UI, it could be any type of application. For example, most mobile apps are written natively to the mobile environment (iPhone or Android, for the most part), and will continue to be at least until HTML5 is fully baked.

Even when the client is a browser, however, we have numerous ways of maintaining application state. Each approach, as you might expect, has its strengths and weaknesses:

Cookies - long a part of the HTTP protocol, cookies are universally supported and almost as universally reviled. We love them for enabling the "remember me" feature on Web sites with logins we visit frequently, and we hate them for enabling advertisers to track our browsing habits. Few app developers would rely on them for much else.

Hidden form fields - every Web developer's secret sauce. You can put whatever you want into such fields, and as long as the user submits the corresponding form, the contents of hidden fields go along for the ride. The problem is that hidden form fields only work with POST. In REST, POST is only for initializing a subsidiary resource, so if that's not what you're doing, then you don't want to POST. The other downside to hidden form fields is that application state information must always make a round trip to the server and back again, whether the server needs to do anything with it or not.

Frames - Frames made their debut in 1996 in Netscape Navigator 2.0, the same browser that introduced JavaScript to the world. Iframes came soon after. Both types of frames allowed new pages in the frame while maintaining state information in JavaScript variables in the enclosing page. In either case, however, updating the content of a frame doesn't change the URL in the browser's location field. As a result, reloading or following a bookmarked page takes you back to square one, deleting all state information.

JavaScript-only updates - More recent advances to the Document Object Model (DOM), in particular the innerHTML property, allow JavaScript to update any <div> element after the page is loaded. And since JavaScript can also perform all manner of RESTful calls, it's possible to make it appear that any or all of a page is changing, even though the page itself isn't actually reloading. As with frames, JavaScript variables can store state information, but also similar to frames, the URL the user sees doesn't change when your script interacts with the server.

Signed scripts - What about simply writing arbitrary content to the user's hard drive? Browser publishers have been monkeying with this capability since signed scripts debuted in the 1990s. The problem with giving the browser write privileges, of course, is security. One flaw and hackers can easily take over your computer. Needless to say, this capability never took off, although plugins like Adobe Flash can allow the ability to write to the users' hard drive.

DOM storage - Today we have DOM storage. Think cookies on steroids. Every modern browser can essentially store a JSON object that persists as the browser loads different pages. You have the option of maintaining such information for a browser session (you lose it when you quit the browser) or persisting it across browser sessions (where the browser writes the data to a file). This capability also enables developers to write browser apps that can function properly when the user is offline. The downside to DOM storage is that it only works in newer browsers - although Firefox, Internet Explorer, Chrome, and Safari all support it.

URL query string - finally, let's discuss storing state information in the URL. Yes, there's a character limit - the HTTP spec recommends sticking to 255 characters or less, although most browsers and Web servers support much longer URLs. So, how much can you cram into 255 characters? More than you might expect, if you use a tool like RISON for compacting JSON to squeeze more of it into each URL. Don't like RISON? There are alternatives available or you can create your own approach. Even with such techniques, however, there is still a size limit, and all such information must make the round trip to server and back.

The ZapThink TakeBased on the discussion above, you should have no more concerns about storing application state on the client. There are always tradeoffs, but one of the scenarios above should handle virtually every application state issue you're likely to come up with. Feel free to transfer application state to the client and rest assured you're following REST.

That is, of course, if you really are following REST, which means that you're building a hypermedia application. And while POST, PUT, and DELETE update resource state for hypermedia applications, every representation from resource back to client updates client state. Even a GET, which never changes resource state, still changes the application state. In other words, clicking a link or submitting a form loads a new page. Of course REST behaves that way.

While this article focused more on maintaining state on the client, therefore, REST is more concerned with updating state on the client. The real point here is that we have the luxury of choosing to maintain the state information we require while running an application whose state is supposed to change. Either way, hypermedia are the engine of application state.

Jason Bloomberg is the leading expert on architecting agility for the enterprise. As president of Intellyx, Mr. Bloomberg brings his years of thought leadership in the areas of Cloud Computing, Enterprise Architecture, and Service-Oriented Architecture to a global clientele of business executives, architects, software vendors, and Cloud service providers looking to achieve technology-enabled business agility across their organizations and for their customers. His latest book, The Agile Architecture Revolution (John Wiley & Sons, 2013), sets the stage for Mr. Bloomberg’s groundbreaking Agile Architecture vision.

Mr. Bloomberg is perhaps best known for his twelve years at ZapThink, where he created and delivered the Licensed ZapThink Architect (LZA) SOA course and associated credential, certifying over 1,700 professionals worldwide. He is one of the original Managing Partners of ZapThink LLC, the leading SOA advisory and analysis firm, which was acquired by Dovel Technologies in 2011. He now runs the successor to the LZA program, the Bloomberg Agile Architecture Course, around the world.

Mr. Bloomberg is a frequent conference speaker and prolific writer. He has published over 500 articles, spoken at over 300 conferences, Webinars, and other events, and has been quoted in the press over 1,400 times as the leading expert on agile approaches to architecture in the enterprise.

Mr. Bloomberg’s previous book, Service Orient or Be Doomed! How Service Orientation Will Change Your Business (John Wiley & Sons, 2006, coauthored with Ron Schmelzer), is recognized as the leading business book on Service Orientation. He also co-authored the books XML and Web Services Unleashed (SAMS Publishing, 2002), and Web Page Scripting Techniques (Hayden Books, 1996).

Prior to ZapThink, Mr. Bloomberg built a diverse background in eBusiness technology management and industry analysis, including serving as a senior analyst in IDC’s eBusiness Advisory group, as well as holding eBusiness management positions at USWeb/CKS (later marchFIRST) and WaveBend Solutions (now Hitachi Consulting).

SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA.
For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.

For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space.
In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...

The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.

Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy.
How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...

MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs.
The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.

Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world.
Get ready to learn the facts:
Is there a bias against women in the tech / developer communities?
Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions?
Some beginnings of what to do about it!
In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...

In his keynote at 16th Cloud Expo, Rodney Rogers, CEO of Virtustream, discussed the evolution of the company from inception to its recent acquisition by EMC – including personal insights, lessons learned (and some WTF moments) along the way. Learn how Virtustream’s unique approach of combining the economics and elasticity of the consumer cloud model with proper performance, application automation and security into a platform became a breakout success with enterprise customers and a natural fit for the EMC Federation.

The Internet of Things is not only adding billions of sensors and billions of terabytes to the Internet. It is also forcing a fundamental change in the way we envision Information Technology. For the first time, more data is being created by devices at the edge of the Internet rather than from centralized systems. What does this mean for today's IT professional?
In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists addressed this very serious issue of profound change in the industry.

Discussions about cloud computing are evolving into discussions about enterprise IT in general. As enterprises increasingly migrate toward their own unique clouds, new issues such as the use of containers and microservices emerge to keep things interesting.
In this Power Panel at 16th Cloud Expo, moderated by Conference Chair Roger Strukhoff, panelists addressed the state of cloud computing today, and what enterprise IT professionals need to know about how the latest topics and trends affect their organization.

It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society-changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed.
In his session at @ThingsExpo, Jason Mondanaro, Director, Product Management at Metanga, discussed how you can plan to cooperate, partner, and form lasting all-star teams to change the world and it starts with business models and monetization strategies.

Converging digital disruptions is creating a major sea change - Cisco calls this the Internet of Everything (IoE). IoE is the network connection of People, Process, Data and Things, fueled by Cloud, Mobile, Social, Analytics and Security, and it represents a $19Trillion value-at-stake over the next 10 years.
In her keynote at @ThingsExpo, Manjula Talreja, VP of Cisco Consulting Services, discussed IoE and the enormous opportunities it provides to public and private firms alike. She will share what businesses must do to thrive in the IoE economy, citing examples from several industry sectors.

There will be 150 billion connected devices by 2020. New digital businesses have already disrupted value chains across every industry. APIs are at the center of the digital business. You need to understand what assets you have that can be exposed digitally, what their digital value chain is, and how to create an effective business model around that value chain to compete in this economy. No enterprise can be complacent and not engage in the digital economy. Learn how to be the disruptor and not the disruptee.

Akana has released Envision, an enhanced API analytics platform that helps enterprises mine critical insights across their digital eco-systems, understand their customers and partners and offer value-added personalized services.
“In today’s digital economy, data-driven insights are proving to be a key differentiator for businesses. Understanding the data that is being tunneled through their APIs and how it can be used to optimize their business and operations is of paramount importance,” said Alistair Farquharson, CTO of Akana.

Business as usual for IT is evolving into a "Make or Buy" decision on a service-by-service conversation with input from the LOBs. How does your organization move forward with cloud? In his general session at 16th Cloud Expo, Paul Maravei, Regional Sales Manager, Hybrid Cloud and Managed Services at Cisco, discusses how Cisco and its partners offer a market-leading portfolio and ecosystem of cloud infrastructure and application services that allow you to uniquely and securely combine cloud business applications and services across multiple cloud delivery models.

The enterprise market will drive IoT device adoption over the next five years.
In his session at @ThingsExpo, John Greenough, an analyst at BI Intelligence, division of Business Insider, analyzed how companies will adopt IoT products and the associated cost of adopting those products.
John Greenough is the lead analyst covering the Internet of Things for BI Intelligence- Business Insider’s paid research service. Numerous IoT companies have cited his analysis of the IoT. Prior to joining BI Intelligence, he worked analyzing bank technology for Corporate Insight and The Clearing House Payment...

"Optimal Design is a technology integration and product development firm that specializes in connecting devices to the cloud," stated Joe Wascow, Co-Founder & CMO of Optimal Design, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.

SYS-CON Events announced today that CommVault has been named “Bronze Sponsor” of SYS-CON's 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. A singular vision – a belief in a better way to address current and future data management needs – guides CommVault in the development of Singular Information Management® solutions for high-performance data protection, universal availability and simplified management of data on complex storage networks. CommVault's exclusive single-platform architecture gives companies unp...

Electric Cloud and Arynga have announced a product integration partnership that will bring Continuous Delivery solutions to the automotive Internet-of-Things (IoT) market. The joint solution will help automotive manufacturers, OEMs and system integrators adopt DevOps automation and Continuous Delivery practices that reduce software build and release cycle times within the complex and specific parameters of embedded and IoT software systems.

"ciqada is a combined platform of hardware modules and server products that lets people take their existing devices or new devices and lets them be accessible over the Internet for their users," noted Geoff Engelstein of ciqada, a division of Mars International, in this SYS-CON.tv interview at @ThingsExpo, held June 9-11, 2015, at the Javits Center in New York City.

Internet of Things is moving from being a hype to a reality. Experts estimate that internet connected cars will grow to 152 million, while over 100 million internet connected wireless light bulbs and lamps will be operational by 2020. These and many other intriguing statistics highlight the importance of Internet powered devices and how market penetration is going to multiply many times over in the next few years.

DevOps is first and foremost a mindset – any DevOps initiative must begin with a cultural change. Last Tuesday, I participated in an online panel on the subject of Implementing a DevOps Culture, as part of Continuous Discussions (#c9d9), a series of community panels about Agile, Continuous Delivery and DevOps. Watch a recording of the panel:
Continuous Discussions is a community initiative by Electric Cloud, which powers Continuous Delivery at businesses like SpaceX, Cisco, GE and E*TRADE by au...

You often hear the two titles of "DevOps" and "Immutable Infrastructure" used independently.
In his session at DevOps Summit, John Willis, Technical Evangelist for Docker, covered the union between the two topics and why this is important. He provided an overview of Immutable Infrastructure then showed how an Immutable Continuous Delivery pipeline can be applied as a best practice for "DevOps." He ended the session with some interesting case study examples.

Business and IT leaders today need better application delivery capabilities to support critical new innovation. But how often do you hear objections to improving application delivery like, "I can harden it against attack, but not on this timeline"; "I can make it better, but it will cost more"; "I can deliver faster, but not with these specs"; or "I can stay strong on cost control, but quality will suffer"? In the new application economy, these tradeoffs are no longer acceptable. Customers will ...

Technology changes at the speed of light. To say it can be hard to keep up is an understatement. For performance engineers, taking charge of your own continuing education is one of the most important things you can do to remain at the top of your game.

JavaScript is primarily a client-based dynamic scripting language most commonly used within web browsers as client-side scripts to interact with the user, browser, and communicate asynchronously to servers.
If you have been part of any web-based development, odds are you have worked with JavaScript in one form or another. In this article, I'll focus on the aspects of JavaScript that are relevant within the Node.js environment.

Most developers learn best by examples, which naturally tend to simplify matters and omit things that aren’t essential for understanding. This means that the “Hello World” example, when used as starting point for an application, may be not suitable for production scenarios at all.
I started using Node.js like that and I have to confess that it took me almost two years to quantify the huge performance impact of omitting a single environment variable. In fact it was just a coincidence that I even...

It is interesting to me, how quickly the hype cycle of a good thing can turn it into a monster that will inevitably eat itself, leaving a much smaller – and much more useful – concept or toolset behind. It has happened over and over in high tech, one need only say “XML” to understand what I mean. It is definitely a useful tool for some jobs, but the “XML Everywhere” craze was insane. People declaring such patently false ideas as “It will end the need for programmers.”

As companies embrace the DevOps movement, they rely heavily on automation to improve the time to market for new features and services. DevOps is a long, never-ending journey with a goal of continuously improving the software delivery process, resulting in better products and services and, ultimately, happier customers. At the beginning of their DevOps journeys, many companies focus on continuous integration (CI), in which they automate the build process. Automated testing is implemented so that ...

It's been three years since I compared medieval security to web security, and a few things have happened. Mobile and wireless have evolved as the dominant platforms, while the life between personal computing and business computing has continued to fray. And, of course, thanks to web services, the web-delivered API now dominates the connected world.
It's time to take a second look, focusing on the API. That is, if our organization is a castle, then the API is the unique services that people ca...

In their session at DevOps Summit, Asaf Yigal, co-founder and the VP of Product at Logz.io, and Tomer Levy, co-founder and CEO of Logz.io, will explore the entire process that they have undergone – through research, benchmarking, implementation, optimization, and customer success – in developing a processing engine that can handle petabytes of data.
They will also discuss the requirements of such an engine in terms of scalability, resilience, security, and availability along with how the archi...

"To us DevOps is actually a movement that at the very center is about developers and IT operations teams collaborating in a framework that drives agility, drives the ideation to production readiness in a seamless manner," explained Monish Sharma, Director in PwC's consulting business, in this SYS-CON.tv interview at @DevOpsSummit, held June 9-11, 2015, at the Javits Center in New York City.

Beginning with Ruxit Agent v1.73, Ruxit provides root cause analysis for Node.js errors down to the code level. As with other services, Ruxit marks web requests to Node.js as failed based on the accompanying HTTP error code.
Simply click the Failure rate portion of any Node.js service infographic to view the Failure analysis chart. If you have failures, click the View details of failures button to see which requests failed along with an overview of failure reasons sorted by HTTP code. You can s...

One of the ways to increase scalability of services – and applications – is to go “stateless.” The reasons for this are many, but in general by eliminating the mapping between a single client and a single app or service instance you eliminate the need for resources to manage state in the app (overhead) and improve the distributability (I can make up words if I want) of requests across a pool of instances. The latter occurs because sessions don’t need to hang out and consume resources that could ...

SYS-CON Events announced today that Logz.io has been named a “Bronze Sponsor” of SYS-CON's @DevOpsSummit Silicon Valley, which will take place November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA.
Logz.io provides open-source software ELK turned into a log analytics platform that is simple, infinitely-scalable, highly-available, and secure.
For more information, visit http://logz.io/.

Much has already been written about the virtues of Docker, and containers in general like CoreOS or Kubernetes. How life-changing Docker is, how innovative, etc. However, the real secret to Docker's success in the marketplace is the hidden retribution of innovation. Innovation and R&D is the lifeblood of today's technology success. Companies, no matter how large, must iterate constantly to stay ahead of their legacy competitors and new upstarts risking disruption. The rise of Agile methodologies...

Approved this February by the Internet Engineering Task Force (IETF), HTTP/2 is the first major update to HTTP since 1999, when HTTP/1.1 was standardized. Designed with performance in mind, one of the biggest goals of HTTP/2 implementation is to decrease latency while maintaining a high-level compatibility with HTTP/1.1. Though not all testing activities will be impacted by the new protocol, it's important for testers to be aware of any changes moving forward.

Brand owners are caught in a digital crossfire.
From one direction comes intense competitive pressure to innovate or to at least follow very, very quickly. From the precisely opposite direction comes the potentially existential threat of an app very publicly flopping or – even worse – being very publicly revealed to jeopardize the customer’s well-being.
Either way, you lose brand value in a social marketplace where brand is your primary currency.
What’s a brand owner to do?

A website visit may involve a wide range of components many of which are off-site or not easily monitored. So what do you have in your toolbox to help address this? Load testing, real-user monitoring and site instrumentation all help you prepare for and monitor your website visitors’ experiences. But one more tool that’s essential for a performance engineer is synthetic user monitoring. It’s a critical part of a web monitoring strategy, however for many people, it’s uncharted territory. So, in t...

Stage setting: Camera is positioned above the treetop of one of three tall poplars. It looks down on the terrace of a pub. It’s evening, but there’s still enough light to see that the terrace is sparsely populated.
Camera slowly moves down towards a specific table in the corner…
As the camera moves down, an old, crummy typewriter font appears on the screen, typing with distinct sound. It spells:

This week, I joined SOASTA as Senior Vice President of Performance Analytics. Given my background in cloud computing and distributed systems operations — you may have read my blogs on CNET or GigaOm — this may surprise you, but I want to explain why this is the perfect time to take on this opportunity with this team. In fact, that’s probably the best way to break this down. To explain why I’d leave the world of infrastructure and code for the world of data and analytics, let’s explore the timing...

Cloud computing budgets worldwide are reaching into the hundreds of billions of dollars, and no organization can survive long without some sort of cloud migration strategy. Each month brings new announcements, use cases, and success stories.